1. Field of the Invention
The present invention relates to apparatus for shutting off and controlling well blowouts, and more particularly, but not by way of limitation, to apparatus for temporary attachment to the top of a well conduit string during an uncontrolled well fluid blowout whereby the well fluid flow can be shutoff and drilling mud or other weighted fluid for killing the well pumped through the apparatus and into the well.
2. Description of the Prior Art
Many various methods and apparatus have been devised for shutting off and controlling well blowouts. In drilling well bores into subterranean fluid producing formations it is common practice to circulate drilling mud through the drill string to the bottom of the well bore and upwardly through the annulus between the drill string and the walls of the well bore. The function of the drilling mud, among others, is to lubricate the drill bit, to carry cuttings produced by the drill bit to the surface where they are separated from the drilling mud and to exert sufficient hydraulic pressure on the bottom of the well bore so that pressurized fluids contained in formations through which the well bore is drilled are prevented from flowing into the well bore. In order to insure the drilling mud exerts sufficient pressure on the bottom of the well bore to prevent formation fluids from flowing into the well bore, weighting materials are commonly added to the drilling mud to increase the density thereof. However, in spite of this and other precautions taken by the operators of well bore drilling apparatus, blowouts often occur. That is, a formation is penetrated by the drill bit containing fluids, e.g. natural gas, under a pressure sufficient to overcome the hydrostatic head exerted on the well bore by the drilling mud, which fluids travel up the annulus between the drill string and the well bore. In severe cases, the pressurized formation fluids force the drilling mud out of the well bore, blow out through apparatus at the ground surface and catch fire. Such blowouts and ensuing fires generally melt the surface drilling equipment and the resulting uncontrolled flow of well fluids and fire are extremely difficult to shutoff and extinguish.
Heretofore developed and used blowout preventer apparatus are not always effective in stopping a blowout, and consequently, elaborate and extremely expensive techniques are often necessary to bring a blowout under control. For example, where a blowout has occurred and the well fluids ae burning, explosives are often used to extinguish the fire followed by the placement of elaborate shutoff apparatus on the casing or conduit string through which the blowing out fluids are flowing. Once the flow of well fluids has been shutoff, a high density weighted drilling mud or other fluid must be pumped into the well bore to kill the well, i.e. terminate the flow of formation fluids into the well bore.
By the present invention relatively simple, inexpensive apparatus is provided for temporary attachment to the top of a conduit string disposed in a well bore during a blowout to shutoff the flow of fluids through the conduit and kill the well.